<Abstract>

Magnetic materials with excellent performances are desired for functional

applications. Based on the high-entropy effect, a system of

CoFeMnNiX (X = Al, Cr, Ga, and Sn) magnetic alloys are designed and investigated.

The dramatic change in phase structures from face-centered-cubic (FCC) to

ordered body-centered-cubic (BCC) phases, caused by adding Al, Ga, and Sn in

CoFeMnNiX alloys, originates from the potent short-range chemical order in the

liquid state predicted by ab initio molecular dynamics (AIMD) simulations.

This phase transition leads to the significant enhancement of the saturation

magnetization (M_s), e.g., the CoFeMnNiAl alloy has M_s of 147.86 Am²/kg.

First-principles density functional theory (DFT) calculations on the electronic

and magnetic structures reveal that the anti-ferromagnetism of Mn atoms in

CoFeMnNi is suppressed especially in the CoFeMnNiAl HEA because Al

changes the Fermi level and itinerant electron-spin coupling that lead to ferromagnetism.
<全文連結>